@pparent
I can't say I've seen this error before, but "Failed to find block device ..." sounds like a partition or mapping issue (which not sure why downgrading from 2.x to 1.x would lead to the unexpected block device mapping for the upgrade back to 2.x).
Did you have a chance to take a look at the recovery logs per the last message line in your screenshot? Perhaps it may provide some additional clues to the root issue.
Although not ideal, you could always fall back to the option to use MSMTools and put a clean install of Oxygen firmware and then let the UBPorts installer install 2.x. Hopefully, someone else chimes in with a proper, simpler fix however.
Let us know what you find out.